GT-20 GT-22 2-Channel, High-Current/High-Power Amplifiers
Table of Contents Parts List Features and Specifications Control Functions Control functions (cont.) Mechanical Functions Recessed RCA inputs Control cover removal & reinstallation Multi-position mounting feet Vents (side & rear) Mechanical functions (cont.
Parts List Included Hardware: GT-20 & GT-22 (1) owner’s manual (1) female quick-connect terminal (1) 2mm hex wrench (for speaker input) (1) 3mm hex wrench (for power input) (4) mounting screws Features and Specifications GT-20 & GT-22 Features 2-Channel, High-Current Amplifier 2Ω Mono Operation Power Increase with Input Voltage Rise Advanced Cooling Allows Varied Mounting Positions Adjustable Feet for Varied Mounting Surfaces Continuously Variable Crossover and Q-factor Settings Selectable Highpass, Lowpa
Control Functions 3 6 5 4 7 GT-22 Top Panel Shown 1 2 8 GT-22 Front Panel Shown 1 RCA Inputs RCA cables from head unit or from other line level device should be connected here. Use both inputs (L & R) for stereo; use “L” input for mono. 2 Remote Input Use the supplied FEMALE quick-connector to connect the REMOTE trigger lead from the head unit to the amplifier. Amplifier turns “ON” when head unit is turned “ON.” One FEMALE .210" connector is supplied with amplifier.
Control Functions (cont.) 6 Lowpass Crossover Controls To use 12dB/octave crossover, move switch to right-hand position. Lowpass crossover frequency is adjustable from 50Hz to 350Hz by rotary control. (Moving switch to left-hand position will bypass crossover functions.) 7 “Q” Control The “Q” Control is active when the highpass crossover is engaged and is centered on the selected crossover point. The range of operation is 0.7–1.2. dB Q +1.6dB 0dB -3dB .707 .95 1.
Mechanical Functions Recessed RCA Inputs The input jacks are recessed into the body of the amplifier to provide clearance in tight mounting locations. 1 inch 1 inch Control Cover Removal & Reinstallation The cover panel is secured with two (2) captive coin-slotted screws. Coin-slotted screws allow a coin edge to be used as a screwdriver to remove the panel. Multi-position Mounting Feet The mounting feet are designed to slide in both directions to clear installation obstructions on the mounting surface.
Mechanical Functions (cont.) Amplifier Linking The design of the side panels enables multiple amplifiers to be used together without additional hardware. Wire Connection Amplifier accepts stripped wire directly into the terminal blocks. Speaker outputs accept 8-gauge, and the DC power and ground accept 4-gauge. Tighten with supplied hex wrenches. Fuses Amplifier accepts standard AT-style automotive blade fuses.
General Installation Precautions WARNING! Before driving the amplifier mounting screws through any surface, be sure of what is behind that surface. Check for the gas tank, brake lines, and any vehicle wiring harness. Never run wires outside or under the vehicle or where they could become broken or interfere with the safe operation of the vehicle. Before You Install Before you install the unit, disconnect the negative (–) battery cable in the engine compartment of the vehicle.
Installation—Amplifier Mounting Choose the Mounting Location Plan your installation so that the amplifier is mounted where adequate ventilation is available. Never mount an amplifier in the engine compartment of a vehicle! WARNING! Before driving the mounting screws through any surface, be sure of what is behind that surface. Check for gas tank, brake lines, and any vehicle wiring harness. 13mm (0.5") 225mm (9") GT-22 GT-20 57mm (2.5") GT-20 GT-22 57mm (2.
Installation—Amplifier Mounting (cont.) Passenger & Trunk Compartment Mounting If the amplifier is mounted under a seat, be sure that the vents do not become blocked. Do not allow seat padding or other obstructive material to press down on the amplifier. All Boston GT amplifiers have top panel controls. If the amplifier is mounted under a seat, position the amplifier so the cover panel can be removed with the seat forward or back to allow adjustment of the audio settings.
Installation—Fuses & Wiring (cont.) Power/B+ & Power/GND Connection Strip approximately 5/8" (16mm) of insulation. The positive (+) power wire is installed into the amplifier terminal marked “B+”. The negative (–) wire is installed into the terminal marked “GND”. The ground wire should be as short as possible and connected directly to the chassis of the vehicle.
Installation—Fuses & Wiring (cont.) Mono Subwoofer Operation When the amplifier is configured for mono operation, use the speaker output terminals marked for mono use. WARNING! Subwoofer impedance must not fall below 2 ohms when in MONO mode. 2-ohm minimum Setup Tuning—Full-range Speakers 1) Music The material chosen for head unit/amplifier system setup must be both clear in recording quality and dynamic in amplitude.
Setup Tuning—Full-range Speakers (cont.) 4) Head Unit The head unit should have all controls such as bass, treble, balance, and fader set to the flat or centered position. The volume control should be at the minimum setting. If the head unit has any equalization or bass management features such as boost, they should be defeated at this time. Turn head unit on, and verify that the GREEN status LED is lit on the amplifier.
Setup Tuning—Full-range Speakers (cont.) 8) “Q” Control Once the highpass crossover point has been determined, use the “Q” control to increase the bass information centered around the crossover point. Setting the “Q” control is done in conjunction with setting the levels on the input sensitivity and highpass crossover frequency controls.
Setup Tuning—Subwoofers (cont.) 2) Head Unit The head unit should have all controls such as bass, treble, balance, and fader set to the flat or centered position. The volume control should be at the minimum setting. If the head unit has any equalization or bass management features such as boost, they should be deactivated at this time. Turn head unit on, and verify that the GREEN status LED is lit on the amplifier.
System Examples System A—Full-range Front Speakers to ground fuse + battery terminal 6.5LF to 6.5LF System B—Rear Fill Speakers to ground fuse + battery terminal 6.5LF to 6.
System Examples (cont.) System C—Single Subwoofer (2Ω) to ground fuse to + battery terminal 2Ω 10.5LF System D —Parallel 4Ω Subwoofers (2Ω load) to ground fuse to 4Ω 10.5LF + battery terminal 4Ω 10.
Amplifier Troubleshooting Guide Status LEDs on Amplifier not Lit—Head Unit (Source) Turned “ON” Verify Remote turn-on wire from source to amplifier has proper voltage Power (B+) connections at amplifier, terminal blocks, and battery are secure Ground (GND) connections at amplifier and vehicle chassis are secure Battery B+ fuse is OK Amplifier fuse is OK B+ at battery and B+ at amplifier have proper voltage Status LEDs Lit, no Output from Speakers—Speakers in Normal Operating Condition Verify High-level c
Contact and Warranty Information Limited Warranty (US) For one (1) year from the date of purchase, Boston Acoustics will repair for the original owner any defect in materials or workmanship that occurs in normal use, without charge for parts and labor—when purchased from an authorized Boston Acoustics retailer. If an authorized Boston Acoustics retailer installs your amplifier, the warranty will be extended one (1) additional year.
